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In the badlands of eastern Montana lives a Hereford cow that has given her all for science. Her name is L1 Dominette 01449. Scientists have spent the past six years combing through her DNA. And as NPR's Jon Hamilton reports, that effort has now produced the first full sequence of the bovine genome.
JON HAMILTON: Dominette 01449 is just one cow, but Harris Lewin, a genome biologist, says her genes hold the answer to a profound question.
Professor HARRIS LEWIN (Institute for Genomic Biology, University of Illinois): What is the essence of bovinity? What makes a cow a cow?
HAMILTON: Lewin, who directs the Institute for Genomic Biology at the University of Illinois, says now we know, or at least we know more than we did.
HAMILTON: He says a comparison of the bovine genome to sequences from humans, dogs and rodents revealed a lot of similarities. Cows are genetically more like humans than mice are, by the way. But there were also some important differences.
Prof. LEWIN: For cattle we have found some extraordinary duplications and expansions of specific genes that are related to milk production, disease resistance and reproduction that differentiate the genomes of cattle from all other genome study to date.
HAMILTON: Those genetic additions probably explain how cattle can produce so much milk, can resist the diseases that attack herd animals. But sometimes less is more when it comes to genes. For example, cattle can digest things humans can't, even though they lack some of our digestive genes. Kim Worley at the Baylor College of Medicine says this may be possible because cattle have outsourced a lot of their digestive work over the past 100 million years. She says it's been turned over to a huge number of bacteria that live in one of the four chambers of the bovine stomach.
Dr. KIM WORLEY (Baylor College of Medicine): So, there are metabolic pathway genes that are found in humans that are not seen in the cattle and that may be because the bacteria have taken up that function and the cattle no longer need to provide those functions.
HAMILTON: Cows aren't the only creatures who need to convert stuff like prairie grass into fuel. It's something people are trying to master as we search for new ways to power cars and produce electricity. Harris Lewin says the bovine genome project should make that easier.
Prof. LEWIN: Knowing how the bugs in the cow's stomach do it is going to help us to learn how to release that energy from those plants for creating renewable energy.
HAMILTON: But Lewin says in the short term the genome will be most useful to the beef and dairy industries. So far, he says, they've had to rely mostly on old-fashioned breeding techniques to do things like identify a bull whose female offspring will produce a lot of milk.
Prof. LEWIN: Now, for example, you can select that individual directly based on his genotype, rather than waiting for several years until his daughters are born, have had their first lactation and then make the selection of the individual for breeding purposes.
HAMILTON: People have been selectively breeding cattle for thousands of years, which has raised some concerns among scientists. Too much inbreeding can reduce genetic diversity and leave animals vulnerable to diseases. The DNA from Dominette 1449 and several other breeds suggest that this is not a problem for cattle — at least not yet. Richard Gibbs directs the Human Genome Sequencing Center at Baylor.
Dr. RICHARD GIBBS (Human Genome Sequencing Center, Baylor College of Medicine): So one of the findings of the study was that the process of selective breeding since domestication has not driven down the diversity to such an alarming level that we should worry that the diversity is not present to allow us to do yet more selective breeding.
HAMILTON: All of which may not matter much to Dominette 1449 out there in eastern Montana. She has other concerns. Dominette turned eight a couple of weeks ago, and she's expecting a calf this fall. The bovine genome research appears in the current issue of the journal Science.
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